1. Field of Invention
The present invention concerns a spot light-source device used in light-sources for liquid-crystal projectors or optical fiber that use spot light-source discharge lamps.
2. Description of Related Art
In recent years, liquid-crystal projectors have come into extensive use as presentation tools at conferences or expositions. Liquid-crystal pictures are projected onto screens via high brightness light sources, but conventional high brightness light-sources for projection by liquid-crystal projectors have had a pair of electrodes facing each other disposed within a discharge envelope made of silica glass. Metal halide lamps having prescribed luminous material sealed within a glass bulb or ultra-high-voltage mercury lamps have been used. Such lamps have been sealed by metal foil seals or rod seals, and external lead members have protruded from such lamps.
However, the demand for greater brightness of projected pictures by liquid-crystal projectors has risen in recent years. Accordingly, higher brightness has also been demanded of light-sources used for projection.
In particular, ultra-high voltage mercury lamps with high sealed pressure foil seals have become the main light source. However, the high brightness that can be attained by light sources is anticipated to reach a limit in the near future since ultra-high voltage mercury lamps sealed by foil seals have limits on the pressure which the sealing sections can withstand.
On the other hand, electrode-free lamps that lack foil seal units as substitute light-sources for projectors have been considered in terms of withstand pressure. An example is the microwave discharge lamp disclosed in the gazette of Japanese Kokai Publication Hei-11-54091. However, such a discharge method is stable tube-wall type discharge in which discharge is generated along the tube walls. The spot light source required of projector light sources is not attained since discharge occurs along the tube walls of a discharge envelope.
In addition, techniques using electrode-free lamps without a foil seal unit as illumination devices are disclosed in the gazettes of Japanese Kokai Publication Hei-6-162807 and Japanese Kokai Publication Hei-9-17216. However, the illumination devices stated in both gazettes are electrode-free lamps. Discharge cannot focus on the lamp center since these are stable tube-wall type discharge lamps similar to those in the gazettes. A spot light source, which is the requisite condition of high brightness discharge lamps, cannot be realized unless the discharge envelopes themselves are miniaturized. Silica glass and alumina which that are material comprising luminous tubes do not permit envelope miniaturization because they can only withstand temperatures under 1200xc2x0 C.
Thus, an object of the invention of this application is to provide a spot light-source device for use in the light source of liquid-crystal projectors that employs lamps whose sealing sections can withstand high pressure.
Another object of the invention of this application is to provide a spot light-source device used as the light source of liquid-crystal projectors that employ spot light-source lamps that have high brightness emission.
A further object of the present invention is to provide a spot light-source device used as the light source for liquid-crystal projectors employing a high-brightness lamp as the spot light source whose sealing sections withstand high pressures.
To resolve the mentioned issues, the present invention provides a spot light-source device excited by electromagnetic energy which has a lamp that comprises a discharge envelope made of translucent non-conducting material with an expansion part and a tube connected thereto, and a discharge concentrator in which the front tip part is supported by said tube without protruding from the discharge envelope and faces the interior of the discharge space of said expansion part, that intensifies concentration of the electric field in the discharge space and that concentrates discharge, an electromagnetic energy provision source that excites discharge in the discharge concentrator from outside of the lamp, a concave reflection mirror that reflects light from the lamp, and a container with a resonance window that creates electromagnetic energy resonance within which are housed the lamp and the concave reflection mirror, that is sealed to prevent leakage of electromagnetic energy, and that has an aperture mounted that collects light from the lamp and the concave reflection mirror.
The spot light-source device excited by electromagnetic energy has a cylindrical unit that protrudes from the container with a resonance window at which the aperture is formed, and a rod type integrator is disposed within the cylindrical unit.
Furthermore, the invention also includes the use of a plurality of integrator lenses installed within a lattice reticulated frame at a the aperture. The spot light-source device can be excited by electromagnetic energy and can use a single discharge concentrator. Alternatively, the spot light-source device excited by electromagnetic energy can be provided with two discharge concentrators disposed facing each other, with the discharge concentrator disposed on the bottom side of a curved surface of the concave reflection mirror being shorter than the other discharge concentrator.
The concave reflection mirror of the spot light-source device excited by electromagnetic energy can be provided with a cooling means that cools the lamp, and the lamp can be provided with a cover member to prevent scattering at the aperture side of the concave reflection mirror. Also, an auxiliary optical system having the function of condensing or reflecting radiated light from the lamp can be provided at the aperture side of the concave reflection mirror of the lamp.
The spot light-source device excited by electromagnetic energy of the invention can be disposed vertically with the concave reflection mirror having an aperture at the bottom of its curved surface.
The spot light-source device of the invention can also be provided with a means of matching the impedance of electromagnetic energy within the container with a resonance window. An insulation space can be provided outside of lamp, and the concave reflection mirror can be made of a dielectric material. Preferably, the dielectric material has a dielectric loss at room temperature of less than 0.1. A wavelength selection film is advantageously formed on the inner surface of the concave reflection mirror, which can be made of metal.
The spot light-source device excited by electromagnetic energy of the invention can be provided with a plurality of electromagnetic energy provision sources, and can be also provided with a plurality of lamps within the container with the resonance window. The electromagnetic energy can be provided from the electromagnetic energy provision source(s) to the container with the resonance window via a coaxial cable or via a waveguide.
When electric field energy is provided in the spot light source device pursuant to the present invention, the spot light source facilitates lighting by concentrating the electric field within the discharge space at the tip of the discharge concentrator during the start of discharge, and by constricting discharge to the tip of the concentrator during normal lighting. By maintaining the discharge concentrator only within the discharge envelope, the resistance to the gas pressure within the discharge envelope during lighting is high due to the absence of sealing sections for current induction member, such as an external lead as is found in conventional lamps having electrodes, for the member to be able to conduct current outside of the discharge envelope. Pictures having high brightness and definition can be provided since the spot light-source device for liquid-crystal projectors uses a lamp having such discharge concentrators. In addition, a device free from leakage of electromagnetic energy can be provided.
Further details, objects and advantages of the spot light-source device according to the invention are described in detail below with reference to the accompanying drawings.